1. Fields of the Invention
The invention relates to a fold-up mechanism for an electric treadmill, and more particularly, to a fold-up mechanism that employs a single lifting motor to bring a main frame in a tilt or a fold-up position.
2. Description of the Related Art
A tilting mechanism of a conventional treadmill is used to adjust the supported angle of a main frame relative to a base frame for creating a certain walking slope. Meanwhile, a fold-up mechanism is used to fold-up the main frame in a storage position for reducing the space occupied by the treadmill. Generally speaking, these can be classified into a manual and an automatic type. The present invention is an improvement of the above-mentioned mechanisms.
U.S. Pat. No. 5,733,228 teaches a mechanism with a lifting motor, pull cable, pulley wheels and return springs to fold-up a main frame of a treadmill between two handrails. Therefore, the main frame can be lifted in a tilt and a fold-up position. Although this prior art has its original design, the mechanism requires complicated and miscellaneous components. In addition, the pull cable and the return springs are subject to fatigue and slack. This is regarded as drawbacks of this prior art.
Another prior art U.S. Pat. No. 6,325,745 teaches a treadmill with its main frame pivotally coupled to a slide groove of a base. Meanwhile, a lifting motor pushes downwardly a supporting rod pivotally attached to the main frame. In this way, the main frame is swivelable in the slide groove to be lifted in a storage position. However, this apparatus doesn't have the function to bring the main frame in a tilt position. Besides, the lifting motor applied its driving force to only one end of the main frame so that the arm of force is evidently mechanically too short. Especially, the lifting motor is movable with the lifting action, and the lifting motor bears all loading created by the main frame. So, the lifting motor is subject to overload that would cause damage to the lifting motor.
A further prior art U.S. Pat. No. 6,015,368 teaches a treadmill with a longer spindle and sleeve to support a rear supporting rod at a bottom end behind a main frame over a long distance to fold-up the main frame. Also, this prior art doesn't have the function of tilting the main frame. Moreover, a lifting motor has to be movable with the lifting action. Thus, it has the same disadvantages as U.S. Pat. No. 6,325,745.